Knight disclosed a torsionally controlled swivel joint in his U.S. Pat. No. 4,111,465 which is illustrated as a component of a flexible conduit system used for loading a tanker track with fluid such as gasoline, oil or water, in which a torque element or torsion spring 25 is retained between two swivel sections to balance any rotational force acting on the two sections. However, Knight's device is preferably suitable for heavy-load application such as used for loading arm and if being applied for a small-load pneumatic swivel system, the internal torsion spring may resiliently force two swivel sections strongly, causing an inconvenient universal rotation for operating the swivel.
Fleckenstein taught a universal pneumatic swivel in U.S. Pat. No. De 270, 369 which is however lacking of an operating handle for rotating the swivel sections and also not provided with a valve means directly in the swivel joint for controlling a flow rate of fluid passing through the swivel joint, to still be unsatisfactory for uses in pneumatic or hydraulic tools.
The present inventor has found the drawbacks of conventional swivels and invented the present universal swivel having a driving handle and valve means.